The present invention relates to a novel pressure monitor and alarm for enclosed pressure or vacuum bodies.
Pressure gages for the measurement of liquids and gases have been applied to many situations where such knowledge is needed. For example, pressure gages have been available to measure the pressure differential between the atmosphere and pressure vessels containing fluids such as air, steam, water and similar materials. The known prior art includes vacuum gages, barometers, manometers, dead-weight piston gages, Bourdon tubes among others.
A problem exists when the pressure measurement must be communicated to an area remote from the user. This has been accomplished in the past by converting the pressure indication into an analogue quantity, for example, a voltage potential, air pressure and the like. One such instrument is the strain gage having varying electrical resistance attached to the surface of a hollow cylinder exposed to the pressure source. The output of this device must be linearized over the range of voltage selected to produce consistant results. Also, the hollow cylinder must be uniformly cast to produce predictable resistance patterns.
A further problem is encountered when the pressure must be remotely indicated in an enclosed body that rotates, such as tires for airplanes, automobiles, trucks, campers, and other vehicles. Further difficulties ensue in the calibration and testing remote pressure sensors in vehicles subject to jarring forces and the general wear and tear associated with motion. Often, alarms and control mechanisms append to pressure sensors. Such devices must be amenable to these necessary modication.